SSH tunnel problem -- buffering data...
From: Brian Genisio (briangenisio_at_yahoo.com)
Date: Thu, 1 May 2003 08:08:08 -0700 (PDT) To: email@example.com
I am using SSH to tunnel (Using LocalForwarding ports) from one application to
another. The system exists of a controller software in Linux (where the SSH
server resides), and the actual software in Cygwin.
Cygwin connects to the Linux SSH server and sets up a port forward. The Linux
app sends a small amount of data (about 12 bytes) 30 times per second.
The problem is that the Cygwin/SSH side of the tunnel is buffering the data
before it sends it to the Cygwin app. The result is the data is received in
bursts, and the control is not fluid.
I have tried this system in a Linux to Linux situation, and the buffering did
not happen. Also, I have tried sending data from Cygwin to Linux, and the
buffering does not happen. It only happens when data is being sent from Linux
I have also tried switching between LocalForward and RemoteForward, and it is
the dirction that matters, not the type of port forwarding.
Both sides sets the TCP_NODELAY flag before it starts sending, and I know the
SSH code does the same...
I should also add that none of this is noticed if SSH is taken out of the loop.
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